Battery modules for installation in electric automobiles, hybrid vehicle, and the like are generally constituted by connecting many electric cells in series via a connection member. This type of battery module needs to be provided with electrical wires for detecting the state (voltage, temperature, etc.) of the electric cell group.
One known example of this battery module is assembled by attaching a wiring module, which includes connection members and electrical wires, to an electric cell group in which multiple electric cells are arranged in a line (e.g., see Patent Document 1).